genirq/proc: Correctly set file permissions for affinity control files

The kernel already knows at the time of interrupt allocation whether
affinity of an interrupt can be controlled by userspace or not.

It still creates all related procfs control files with read/write
permissions. That's inconsistent and non-intuitive for system
administrators and tools.

Therefore set the file permissions to read-only for such interrupts.

[ tglx: Massage change log, fixed UP build ]

Signed-off-by: Jeff Xie <jeff.xie@linux.dev>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20240825131911.107119-1-jeff.xie@linux.dev

diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index 8cccdf40725af5a83aeb19d15c0979882992b54f..9b3b12ad5dda48c04ebb645adf0e2b2f7b1251bb 100644 (file)
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -362,8 +362,13 @@ void register_irq_proc(unsigned int irq, struct irq_desc *desc)
                goto out_unlock;
 
 #ifdef CONFIG_SMP
+       umode_t umode = S_IRUGO;
+
+       if (irq_can_set_affinity_usr(desc->irq_data.irq))
+               umode |= S_IWUSR;
+
        /* create /proc/irq/<irq>/smp_affinity */
-       proc_create_data("smp_affinity", 0644, desc->dir,
+       proc_create_data("smp_affinity", umode, desc->dir,
                         &irq_affinity_proc_ops, irqp);
 
        /* create /proc/irq/<irq>/affinity_hint */
@@ -371,7 +376,7 @@ void register_irq_proc(unsigned int irq, struct irq_desc *desc)
                        irq_affinity_hint_proc_show, irqp);
 
        /* create /proc/irq/<irq>/smp_affinity_list */
-       proc_create_data("smp_affinity_list", 0644, desc->dir,
+       proc_create_data("smp_affinity_list", umode, desc->dir,
                         &irq_affinity_list_proc_ops, irqp);
 
        proc_create_single_data("node", 0444, desc->dir, irq_node_proc_show,